Azo dyestuffs



Patented Feb. 21, 1939 "UNITED STATES PATENT OFFICE AZO DYESTUFFS No Drawing. Application August 18, 1937, Serial 6 Claims.

In our co-pending application Ser. No. 69,592, filed March 18, 1936, Patent No. 2,110,394, issued March 8, 1938, We have described and claimed leather dyed with monoor disazodyestuffs of the general formula:

in which RN=N stands also for the radical of an aromatic diazo compound or a diazoazo compound while R1 stands for a 2-aminonaphthalene coupling component of the general formula:

R (III In the latter formula R2 and R3 designate hydrogen atoms or alkyl or aryl groups.

In the dyestuffs of the above formula (II) to be used in accordance with the present invention, B may for instance mean a radical of the benzene or naphthalene series which may be substituted. Suitable substituents are for instance halogen atoms, such as chlorine or bromine atoms, alkyl groups, such as the methyl or ethyl radicals, nitro groups, acylam'ino groups, alkoxy groups, such as the methoxy or ethoxy group.

R may further be substituted by an aryl azo group so that RN=N stands for a diazoazo group, such for instance as in the case of diazotized aminoazobenzene or diazotized aminoazobenzene-disulfonic acid.

In theaforementioned Formula III, illustrating R1, one or both valences of the nitrogen atom may be linked to hydrogen atoms, alkyl or aryl groups. For instance R1 may stand for 2-aminonaphthalene and N-monoor dialkylated 2- amino-naphthalene, or for a Z-aminonaphthalene, in which for instance one hydrogen atom of the amino group is substituted by an aryl radical.

In Germany August 21, 1936 R2 and R3 can also denote substituted alkyl or aryl radicals. Thus R2 and/or R3 may represent an alkyl group substituted for instance by hydroxyl groups, which latter may, by way of example, be etherified. On the other hand R2 or Rs may stand for an aryl radical, which may be substituted for instance by nitro, alkyl, hydroxy, alkoxy, sulfonic or carboxylic acid groups, as well as halogen atoms.

Also the naphthalene ring system may bear substituents except hydroxyl groups.

Sulfonic acid groups may be present either in R or in R1 or in both ring systems.

In dyeing chrome leather, it is desired not only to dye the surface of the leather, but also to give an even shade'to the cut of the leather to a certain depth of penetration, while the zone of the cross-cut remaining undyed is intended to retain the pure greenish chrome color.

Of particular technical importance are dyeings of this kind on leathers, the grain side or flesh side of which is more or less ground off after the dyeing.

In acordance with the present invention the desired effect is attained to an excellent degree, when in the dyeing process monoor dlsazodyestuffs of the above identified formula are used, the dyeing per se being performed according to the standard methods of dyeing leather, as is more fully described in the annexed examples. If desired the monoor disazodyestuifs of the above identified formula can be used in mixture with other acid or substantive dyestuffs.

The invention is illustrated by the following example without being restricted thereto:

Example 100 kgs. of neutralized chrome calf leather are introduced into a drum with about 300 kgs. of hot water at C. A dyestuff solution prepared from 1.5 kgs. of the dyestuif from diazo-tized 2- chloraniline and Z-naphthylamine-3.6-disulfonlc acid and 40 kgs. of hot water is gradually added. After about 3 quarters of an hour the dyestuff has been absorbed. Stuffing of the leather is then effected. In this manner there is obtained a dyeing of a brownish-yellow shade, which exhibits on the grain side and on the flesh side a distinct dyeing of the out, without changing or soiling the characteristic greenish color of the chrome leathin the interior of the cut. Further, both the flesh and the grain side can be easily ground off, without producing a bad and non-uniform appearance by the standing out of undyed fibres.

The following table contains some further methyl and phenyl, and n stands examples and the shades obtained on leather:

number.

Diazotization component Coupling component Shade Orange.

Rcddish light brown. Orange-brown. Yellowish orange. Brownish red.

2-11agl1thylamine-5.7-disulionic acid Z-naphthylamine 2-metl1ylaminonaphth alene-7-sullonie acid: Phenyl-Z-naplitliylaminefi-sullonic acid.

for a whole 4-acetyletl1ylamino-Z-aminotoluen 10 2-naphthy1aminc-5.7-disulfonic acid 2-naphthylaminc-0.8-disulfonic acid 2.5-dichloraniline 2-chloraniline-4-sulionic acid 4'- nigro-4-aminodiphenylaminc- 2- sulionic aci m-Nitranilinc m-Acetylamino-l-aminobenzcnc Am noazobenzene-sulfonic acid... Aminoazobcnzene-disulfonic acid.

Dc -nitraniline-Z-sulionic acid 2-naghthylamine3.fi-disulionic acido e Phcnyl-2-naphthylaminesulionic acid.

2-aminonaphthalene-3.fi disulfonic acid. 2-na;1 hthylamine-5.7-disulionic acidapht 2-naphtliylamine. Phenyl-2-naphthylamine-fisulfonie acid...

Brownish yellow.

Brownian-orange yellow. Brownish yellow.

Red.

Brown.

Do. Reddish yellow. Durlil yellow.

Re Reddisli bordcaux. Violet.

of the above starting materials, 4-acety1ethy1- amino-Z-amino toluene is obtainable from ptoluidine by ethylation, acetylation and nitration, the nitro group being subsequently reduced to the amino group.

4-nitro-4-aminodiphenylamine-2-sulIonic .acid is obtainable by condensing 4-nitro-1-chlorobenzene-Z-sulfonic acid with p-phenylenediamine.

Besides the excellent dyeing in obtained in a neutral bath, the dyestuffs have in general a good stability and fastness to alkalis and acids.

The dyestuffs in question, besides being suitable for chrome leather, are particularly suitable for dyeing other kinds of leather, especially vegetable and semichrome tanned leather. Of course, they can also be used together with other suitable acid or substantive dyestuffs.

0 We claim:

1. Leather dyed with a dyestuff of the general formula in which R-N=N stands for a member selected from the group consisting of radicals of diazo and diazoazo compounds of aniline and naphthylamine and their halogen, nitro, allzyl, alkoxy, acylamino, alkylamino and arylamino substitution products, X stands for one of the group consisting of hydrogen, methyl and phenyl and n stands for a whole number.

2. Leather dyed with a dyestufr of the-general formula:

in which R--N=N stands for a radical of a diazo compound of the benzene series, X stands for one of the group consisting of hydrogen,

3. Leather dyed with a dyestuff of the general formula:

in which RN=N- stands for a radical of a 5;) diazo compound of the benzene series, and n stands for a Whole number.

4. Leather dyed with a dyestufi of the general formula:

in which RN=N stands for a radical of a r5 diazo compound of the naphthalene series, X stands for one of the group consisting of hydrogen, methyl and phenyl, and n stands for a whole number.

6. Leather dyed with a dyestufl having in the free state the following formula:

NHZ S 03H ERNST FELLMER.

GUSTAV MAUTHE. HERMANN NOERR. 

